1. Field of the Invention
The invention relates to a hybrid vehicle and a method of controlling the hybrid vehicle. In particular, the invention relates to a hybrid vehicle including a filter for trapping particulate matter in exhaust gas of an internal combustion engine, and a method of controlling the hybrid vehicle.
2. Description of Related Art
Exhaust gas emitted from an engine contains particulate matter (which will also be referred to as “PM”). It is preferable not to emit the PM into the atmosphere since the PM may exert an influence on the environment, or the like. Therefore, a filter for trapping the PM may be installed in an exhaust passage of the engine.
When the PM is deposited on the filter, clogging may occur to the filter, and the filter may suffer from erosion or cracks, for example. Accordingly, when the amount of deposition of the PM reaches a given amount, it is necessary to remove the PM so as to recover the filter from clogging. To remove the PM as in this case will be called regeneration of the filter. As specific control for regenerating the filter, it has been proposed to raise the temperature of exhaust gas by increasing the output of the engine, so as to burn the PM.
For example, an engine control device disclosed in Japanese Patent Application Publication No. 2005-90259 (JP 2005-90259 A) is configured to adjust the state of charge (SOC) of a battery so that the battery has some room for charging, when a filter needs to be regenerated in a hybrid vehicle. Thus, when the output of the engine is increased for regeneration of the filter, the battery can be charged with electric power generated by a generator. The electrical power generated by the generator corresponds to an amount of increase of the output of the engine.